yapm ISA

Table of Contents Overview Instruction execution Instruction format Assembler conventions Instruction set reference LD/ST CALL Arithmetic

Overview

Parallel machine is based on VLIW architecture. Some key aspects:

• Memory is direct addressed. Available address space is 0 .. 2^16
• Register space is 256 wide
• 4 asymmetric execution units:
  • Units 0 and 1: operations with memory(ld/st) and control operations(call)
  • Units 2 and 3: basic arithmetic(add, sub, etc.)
• Each operation costs 1 cycle, no memory latency.
• All data has tags. Tags are used to determine data types(int/float/address) and allowed of operations on them.

Instruction execution

Machine executes 1 macrooperation per cycle. Each macrooperation consists of 4 operations - 1 operation per execution unit. So all execution is statically planned by compiler. If some execution unit on some cycle has no command to execute than macrooperation should have "NOP" operation in corresponding slot.

Instruction format

TBD

Assembler conventions

To simplify joint development of binary translator and interpretor assembler has following syntax:

• Operations inside macrooperations are separated by semicolon. At the end of each macrooperation should be caret return. EOL is delimiter of macrooperations.
• Integer constants size is 1 byte(short int), floating point - 2 bytes(half-precision float), address constant - 2 bytes(unsigned word).

Example of assembler code:

LDC 2, r0; NOP; NOP; NOP; 
ST r0, 0; NOP; NOP; NOP; 

Instruction set reference

LD/ST

Instructions in this group are executed on units 0 and 1.

LDC - load constant to register

 ldc <const>, <dest_reg> 

LD - load value from memory to register

 ld <addr>, <dest_reg> 

ST - store value from register to memory

 st <src_reg>, <addr> 

LDA - load value from memory at dynamic address to register

 lda <base_reg>, <index_reg>, <dest_reg> 

STA - store value from register to memory by dynamic address

 sta <base_reg>, <index_reg>, <src_reg> 

CALL

Instructions in this group are executed on units 0 and 1.

CALL - make call of hard-coded function

 call <index> 

Arithmetic

Instructions in this group are executed on units 2 and 3.

ADD , SUB , MUL , DIV , REM , CHSGN